Blast furnace bleeder valve operation



Nov. 9, 1965 Filed June 21, 1960 H. HOLIDAY, JR., ETAL BLAST FURNACEBLEEDER VALVE OPERATION 2 Sheets-Sheet l IN V EN T ORS. HARRY HoL/aA v,J2. BY JOHN W Wu n/vso/v,

ATTORNEYS.

FIG-.2.

1965 H. HOLIDAY, JR., ETAL 3,

BLAST FURNACE BLEEDER VALVE OPERATION Filed June 21, 1960 v 2Sheets-Sheet 2 FIG. 3'.

' L 3/ FIB- 4a 33 IN V EN TORS. HAzev HOLIDA v, Jz, By JOHN W mum/sou,-

ATTORNEYS.

United States Patent 3,216,819 BLAST FURNACE BLEEDER VALVE OPERATIONHarry Holiday, In, and John W. Wilkinson, Middletown,

Ohio, assignors to Armco Steel Corporation, Middletown, Ohio, acorporation of Ohio Filed June 21, 1960, Ser. No. 37,640 7 Claims. (CI.75-41) The invention relates to bleeder valves of blast furnaces. As iswell understood, the ordinary blast furnace has one or more uptakesconnected to the interior of the furnace below the charging bell, andextending upwardly above the top of the furnace. These uptakes serve astake-off means for the furnace gases. They are interconnected usually bya manifold having a downcomer for conducting the furnace gases to asolids separator and thence to a gas washer.

The tops of the uptakes are provided with bleeder valves which areeither manually or automatically operated for the purpose of relievingsudden pressure excesses.

The gases issuing from a blast furnace are at high temperature and havelarge quantities of abrasive solids entrained in them, and are referredto herein by the term dirty gases. The bleeder valves have acomparatively short life. When a valve is opened, there is a rush ofabrasive laden gases through the valve opening so that the membersproviding the valve seat and the valve tappet tend to be cut and scored.When the valve is again closed, the cutting and scoring permits leakageof the gases. Once a bleeder valve begins to leak, the cutting actionproceeds very quickly while the valve is closed due to the erosiveeffect of the abrasive materials entrained in the dirty gases. In modernblast furnaces operating on high top pressures, the cutting action isincreased.

It is an object of the invention to provide a means and method forprolonging the useful service life of dirty gas bleeder valves and forminimizing leakage.

It is an object of the invention to provide a mode of operating thedirty gas bleeder valves which will very greatly prolong their servicelife.

It is an object of the invention to minimize leakage from dirty gasbleeder valves, not only by reducing the wear which has been describedabove, but also by providing, in one of the aspects of the invention, asealing action which tends to close leakage orifices previously formed.

These and other objects of the invention which will be set forthhereinafter, or will be apparent to one skilled in the art upon readingthese specifications, are accomplished by that structure and arrangementof parts of which certain exemplary embodiments will now be described.Reference is made to the accompanying drawings wherein:

FIG. 1 is a top plan view of one form of bleeder valve.

FIG. 2 is a vertical sectional view thereof.

FIG. 3 is a vertical sectional view of another type of bleeder valve.

FIG. 4 is a diagrammatic view of the top portion of a blast furnaceincluding uptakes, gas handling equipment including a solids separatorand a gas washer, and a means for returning clean gas to the bleedervalves.

In FIG. 2 the upper end of an uptake is indicated at 1. The bleedervalve proper includes a bowl-shaped casting 2 having at the top a castelement 3 of annular form which serves as a valve seat. A shaft 4 isjournaled in brackets 5 and 6 on the bowl; and it will be seen fromFIGS. 1 and 2 that this shaft bears centrally a lever arm 7 which isconnected to a valve disc or tappet 8. One end of the shaft 4 carries alever arm 9 counterweighted as at 10 and provided at its opposite endwith an operating 3 ,2 16,81 9 Patented Nov. 9, 1965' cable 11. Withinthe bowl 2 there are guide elements 12 for the movement of the tappet 8.

It will be noted that the valve shown in FIGS. 1 and 2 is an inwardlyopening valve. It must be operated by the cable 11 whenever relief ofpressure is desired; and as is well known in the art, the operation canbe accomplished either manually or by automatically acting means.

Another form of valve is shown in FIG. 3. This valve also has a bowl 13located at the top of an uptake 14. There is a superstructure 15 on thetop of the bowl, which provides support for a bracket 16, and which alsocarries a cast iron valve seat 17. The valve in this instance is anoutwardly opening valve comprising a tappet 18 lying above the valveseat 17. An operating lever arm 19 is pivoted to the bracket 16 and alsoto a valve stem 20. The lever arm 19 is counterweighted as at 21 to holdthe valve closed; and it will also be provided with an operating cable,not shown.

It is frequent in valves of this type to provide an in ner bell-shapedvalve guide 22 attached to the tappet. The bowl provides guides 23 forthe valve bell which, in turn, keeps the valve tappet in alignment withthe seat and which also tends to control the direction of the flow ofgases through the valve. The type of valve shown in FIG. 3 is one whichcan act automatically to relieve the pressures above a certain valuewithin the uptake, as determined by the counterweighting of the leverarm 19.

Other types of bleeder valves may be used; but the types shown in FIGS.1, 2 and 3 are exemplary. It will be seen that when the tappet is openedin either type of valve, the rush of dirty abrasive laden gases throughthe space between the valve tappet and the valve seat will tend to cut,score and abrade both of these elements, with the. result that leakagewill develop. Thereupon, as explained above, the cutting action becomeschanneled and is excessive, when the valve is closed, at the placeswhere the leakage occurs, so that the valve seats and tappets have to bereplaced at comparatively short intervals.

The primary objectives of this invention are attained by introducinginto the bowl elements 2 and 13 such quantities of clean gas, i.e. gasfree of abrasive entrainment, as to keep the dirty gases out of the bowland away from the valve seat and tapped when the valve is closed. When avalve is opened to reduce the pressure within the furnace, dirty gaswill issue to the atmosphere through the valve. But the introduction ofclean gases into the bowl is a continuous operation, and as soon as thevalve is again closed, the dirty gases will be swept out of the bowl anddownwardly in the uptake. If some leakage has developed between thevalve tappet and the valve seat, clean gases only will issue from theleakage openings because the clean gases are supplied to the bowl insufficient volume to take care of such leakage. Thus, because the cleangases are substantially free from abrasive entrainment, the leakageopenings will not tend to grow in size.

The gases introduced into the bowl may be from any available source ofclean, compatible gas. By compatible gas is meant any gas which will notattack the apparatus elements or the furnace lining, and which will notreact exothermically with the furnace gases. Thus, nitrogen, argon orthe like could be used; but cost must be considered. The gas should benon-oxidizing. The introduction of air, for example, would create anexplosion hazard. In both FIGS. 2 and 3 there is indicated a gas inletconduit 24 and 25 having a control valve 26 or 27.

One source of clean compatible gas can be the furnace gases themselvesafter they have gone through a solids separator and a gas washer. InFIG. 4 there is shown diagrammatically a blast furnace 28 having uptakes29 and 30 equipped with bleeder valves 32 and 31. The manifold mentionedabove is indicated at 33, carrying the furnace gases to a downcomer 34which delivers them to a solids separator 35 of the usual type. Thegases from the solids separator are carried by a conduit 36 to a gaswasher 37; and the bulk of the treated furnace gases will be carried bya conduit 38 to places of use as is conventional in blast furnacedesign. A branch pipe 39 will carry some of the clean gases back to thebleeder valves 31 and 32, as will be evident from the figure. A boosterpump 40 must be included in the conduit 39 to raise the pressure of theclean gases to a value which is at least somewhat greater than the toppressure of the furnace.

It has been found also that steam from any available source servesexcellently as a clean gas for introduction into the bowls of thebleeder valves. As has been indicated, the clean gas should beintroduced into the bowl elements in such quantity as to keep the dirtygases from the furnace swept out of the bowl. This is easy to accomplishwith clean gases having substantial pressure when the conduits 24 and 25are of relatively small size, but the gas pressure and conduit sizeshould be so related as to supply a sufficient volume of gas for thepurposes herein set forth. The inflow of the clean gases is adjusted bythe valves 26 and 27 so that the bowl is kept filled with the cleangases. The adjustment is not critical beyond the point just mentioned,because any excess gases so introduced will pass downwardly through theuptakes and downcomer and mingle with the furnace gases. As aconsequence, while specific instructions cannot be given as topressures, volumes, conduit sizes and the like, be cause these will varywith circumstances including size of the bleeder valve elements, the toppressure of the furnace, and other factors, a reasonably high pressureof the clean gas is desirable as minimizing the size of the conduits. Byway of non-limiting example, steam, available at 150 p.s.i.g., has beenemployed with a 1 /2 in. diameter conduit 24. The actual adjustment isnot difficult to accomplish. If the valve is leaking, the introductionof clean gas can be controlled until only clean gas is issuing from theleakage openings, as can be visually determined. In the case of a valvehaving a new tappet and seat, a condition of leakage can be simulated byslightly opening or cracking the valve.

The use of steam, however, has been found to have an additional andimportant advantage. There will be some small amount of condensation ofthe steam adjacent the valve parts; and the condensed moisture will tendto form any accumulation of abrasive substances adjacent or between theeoacting parts into a sort of sludge cake, the eifect of which is toseal off leakage at the eoacting valve surfaces. Any excess moisturecondensed in the valve presents no problem since it will pass downwardlyin the uptakes to the furnace gas take-01f point, be revaporized, andpass out of the system with the furnace top gases.

Even where other compatible gas is mainly employed for the purposes ofthis invention, the advantages of the caking action .hereinabovedescribed maybe attained by mixing some steam with the other compatiblegases, or by introducing some steam separately into the bleeder valvebowl.

It has been found that the use of the invention herein described sharplyreduces the cutting action on the'bleeder valve seat and tappet, andvery greatly increases the useful life of these elements. Additionally,in the last mentioned phase of the invention, leakage is to all intentsand purposes stopped, even though the disc and seat are cut and scored.

Modifications may be made in the invention without departing from thespirit of it. The invention having been described in certain exemplaryembodiments, what is claimed as new and is desired to be secured byLetters Patent is:

1. In a blast furnace having at least one uptake for dirty gas, a dirtygas bleeder valve in connection with said uptake having a body, a valveseat, and a valve tappet at the upper end of said body, means foropening said valve, and a means opening into said body for introducingclean compatible gas into said body, said compatible gas being free ofabrasive entrainment, in such quantity as to keep said valve body filledwith said compatible gas during periods of time in which said valveremains in the closed position.

2. In a process of operating a blast furnace having bleeder valves, saidbleeder valves each comprising a body, a valve seat, and a valve tappet,said body being located at the top of an uptake, the improvementcomprising introducing into the body of the valve below said seat andtappet continuously a compatible gas free from entrainment of abrasivesolids in such quantity as to keep dirty furnace gases swept out of saidbody at least when said valve seat and tappet are in the valve-closedposition.

3. The process claimed in claim 2 wherein said compatible gas is steam.

4. The process claimed in claim 2 wherein said compatible gas is gasderived from a blast furnace, which gas has been freed from abrasiveentrainment.

5. The process claimed in claim 2 in which said compatible gas is amixture of steam and another gas free from abrasive entrainment.

6. The structure claimed in claim 1 wherein said means for introducingclean, compatible gas into said body is a means for introducing steamfrom a suitable source thereof.

7. The structure claimed in claim 1 wherein said means for introducingclean compatible gas into said body is a means for introducing top gasesfrom said blast furnace, which top gases have been freed from solidparticles, the said apparatus assembly including a booster pump forincreasing the pressure of said top gases.

References Cited by the Examiner UNITED STATES PATENTS 704,556 7/02Meehan 26626 903,425 11/08 Witting et al 26631 1,335,494 3/20 Haig 2663l2,408,945 10/46 Mohr et al 266-27 2,585,800 2/52 Le Viseur et al. 266-31X FOREIGN PATENTS 15,270 1886 Great Britain.

JOHN F. CAMPBELL, Primary Examiner.

NATHAN MARMELSTEIN, MARCUS U. LYONS,

RAY K. WINDHAM, MORRIS O, VVOLK, Examiners,

1. IN A BLAST FURNACE HAVING AT LEAST ONE UPTAKE FOR DIRTY GAS, A DIRTYGAS BLEEDER VALVE IN CONNECTION WITH SAID UPTAKE HAVING A BODY, A VALVESEAT, AND A VALVE TAPPET AT THE UPPER END OF SAID BODY, MEANS FOROPENING SAID VALVE, AND A MEANS OPENING INTO SAID BODY FOR INTRODUCINGCLEAN COMPATIBLE GAAS INTO SAID BODY, SAID COMPATIBLE GAS BEING FREE OFABRASIVE ENTRAINMENT, IN SUCH QUANTITY AS TO KEEP SAID VALVE BODY FILLEDWITH SAID COMPATIBLE GAS DURING PERIODS OF TIME IN WHICH SAID VALVEREMAINS IN THE CLOSED POSITION.
 2. IN THE PROCESS OF OPERATING A BLASTFURNACE HAVING BLEEDER VALVES, SAID BLEEDER VALVES EACH COMPRISING ABODY, A VALVE SEAT, AND A VALEVE TAPPET, SAID BODY BEING LOCATED AT THETOP OF AN UPTAKE, THE IMPROVEMENT COMPRISING INTRODUCING INTO THE BODYOF THE VALVE BELOW SAID SEAT AND TAPPET CONTINUOUSLY A COMPATIBLE GASFREE FROM ENTRAINMENT OF ABRASIVE SOLIDS IN, SUCH QUANTITY AS TO KEEPDIRTY FURNACE GASES SWEPT OUT OF SAID BODY AT LEAST WHEN SAID VALVE SEATAND TAPPET ARE IN THE VALVE-CLOSED POSITION.